The charge and velocity detector of the cosmic dust analyzer on Cassini

The cosmic dust analyzer aboard the Cassini spacecraft includes a charge and velocity detector which senses electric charges >10−15 C of individual cosmic dust grains as they enter the instrument. Charge is an important property of each grain, because it affects its orbital dynamics and is a measure of its size. The duration and shape of the charge signal are also important, because they reveal the grainʹs location and velocity relative to the spacecraft. The velocity, in turn, can be expressed in a heliocentric coordinate system and orbital parameters can be derived and aid in the identification of the grainʹs origin. We describe the operation of the charge and velocity detector, present results of laboratory calibrations using charged hypervelocity dust particles, show the first dust charge signal obtained from interplanetary space, and discuss potential applications of an advanced charge detector for future space missions.